Skip-stitch mechanism for blindstitch sewing machines



May 18, 1954 F. PARRY 2,678,619

SKIP-STITCH wscmmsu FOR BLIND-STITCH SEWING MACHINES Filed June '2'. 1952 4 Shee'ts-Sheet 1 IN VEN TOR 31 0105 fiw'ry WITNESS BY ATTORNEY May 18, 1954 F. PARRY 2,678,619

SKIP-STITCH MECHANISM FOR BLIND-STITCH SEWING MACHINES Filed June 7. 1952 4 SheetsSheet 2 INVEN TOR i'anfi {film/3 WITNE8S BY ATTORNEY F. PARRY May 18, 1954 SKIP-STITCH MECHANISM FOR BLIND-STITCH SEWING MACHINES Filed June 7, 1952 4 Sheets-Sheet 3 mu mud VA! Al/////////////// fl Nil??? WITNESS May 18, 1954 PA 2,678,619

SKIPSTITCH MECHANISM FOR BLIND-STITCH SEWING MACHINES Filed June 7, 1952 4 Sheets-Sheet 4 INVENTOR. 81 61715 cflzwy WITNESS BY ATTORNEY Patented May 18, 1954 SKIP-STITCH MECHANISM FOR BLIND- STITCH SEWING MACHINES Frank Parry, Trumbull, Conn., assignor to The Singer Manufacturing N. J .,.a corporation of New Jersey Application'June 7, 1952, Serial No. 292,263

9 Claims.

provide a sewing machine having a skip-stitch mechanism in which only the ridge-former is periodically raised and lowered while the worktable is held stationary, thus eliminating the necessity of subjecting the. actuating mechanism of the ridge-former to the additional load or work of overcoming the spring pressure normally exerted to maintain the work-table in its elevated position.

L Still anotherobjectof the present invention is to provide a simplified skip-stitch mechanism for a blind-stitch machine in which the component partsof the mechanism are arranged so that they cangbe made relatively small and light in weight and; whereby the motions required for the operation are small, resulting in small inertia forces withthe consequent smooth high speed operation of. the machine.

.The foregoing and other objects and advantages in view, together with means whereby the same may be carried into effect, will best be un- Jderstood from the following description of a preferred embodiment thereof illustrated in the accompanying drawings, in which:

Fig. 1 is a top plan view of a blind-stitch sewing machine equipped with the present invention,

, certain of the cover-plates being removed and parts of the machine being in section better to show the operating mechanisms of the machine. Fig. 2 represents a vertical sectional view taken substantially along the line 2-2, Fig. 1.

Fig. 3 represents an enlarged horizontal longitudinal sectional view of the work-table taken substantially along the line 3--3, Fig. 2, showing in detail the telescopic shaft arrangement of the skip-stitch mechanism.

Fig.4 represents an enlarged vertical. longitudinal sectional view of theworkrtable taken substantially along-theline 44, Fig. 1.

i Fig. 5 is an end ,elevationof the tubular ridgeformer carrying shaft and its actuating rock- Company, Elizabeth,

lever with the eccentrically bodied internal supporting shaft in section, the view being taken substantially along the line 5-5, Fig. 4.

Fig. 6 is an end elevation of the eccentrically bodied supporting shaft and its actuating rocklever, this view being taken substantially along the line 66, Fig. 4.

Fig. 7 represents an enlarged vertical sectional view through the machine-standard and substantially along the line l'|, Fig. 1, illustrating the manner of supporting and driving the skipstitch eccentric.

Fig. 8 represents a vertical sectional view taken substantially along the line 8-8, Fig. '7.

Fig. 9 represents an enlarged transverse section taken through the work-table substantially along the line 99, Fig. 1, showing the relative location of the ridge-forming element with respect to the stitch-forming mechanism and the feeddog.

Fig. 10 represents an enlarged vertical section taken at the stitching point, showing the needle about to enter the work to form the anchor stitch.

Fig. 11 is a view similar to Fig. 10, but with the ridge-former at its lowered operative position in which the work is presented for the formation of the skip stitch. Referring to the drawings, the sewing machine includes a machine-frame comprising a base having a hollow standard 2| rising from the rear right hand corner thereof. Extending laterally towards the left from the upper end of the standard is a horizontal arm 22, and extending forwardly from the left hand end thereof is an arm 23. Attached to the free end of the arm 23 is a stationary presser-plate or foot 24 against which the work is clamped by a pair of conventional vertically yieldable work-clamping members 25 (Fig. 9)v pivotally supported as at 26, adjacent the free end of a tubular work-table 27 which is supported by the base 29. Coil-springs 28, acting between the work-table 21 and the work-clamping members supporting bell-cranks 29, yieldingly urge the members 25 into work-clamping relation with the presser-plate 24.

Journaled in the horizontal arm 22 is a main rotary shaft 30 which, through the usual connections disclosed for example in the U. S. patent of Dearborn, No. 705,325, July 22, 1902, oscillates a needle-shaft 3| which is suit-ably journaled in the forwardly extending arm 23. Carrled on the forward end of the needle shaft 3| is a curved needle 32 which oscillates directly above the presser-plate 24 and in a path transverse to the longitudinal axis of the needle shaft 3|, the

table 27. 'of the work-table 21 will cause the link 6i (Fig.

sition to the vertically yieldable work-clamping members 25, all in a manner substantially like that disclosed in the U. S. patent of Dearborn, No. 1,592,446, July 13, 1925.

The work to be stitched is supported on the Work-table 2! which is formed at its free left 3 hand end as a tube or horn beneath the stitching and feeding mechanisms and at its right hand end is enlarged into substantially rectangular form having a convex upper surface closed, by a cover-plate (Figs. 2. and 4), and a pair of depending end-walls 35 and 31. The means by which the work-table 2'! is supported and the mechanism for controlling the normal elevated or workin position of the work-table forms the subject of another of my copending applications Serial No. 292,261, filed June '7, 1952, and, therefore, only sufiicient description will be hereinafter given of the support for the work-table as will be necessary for a clear understanding of the present invention. Suffice it to say that the i depending end-walls 36 and 3'? of the work-table 2! are preferably fitted with bushings 38 and 32 (Fig. l) in which are journaled the reduced eccentrically located opposite ends ill and iii of a work-table supporting shaft &2 freely journaled the spaced upstanding lugs 53 and ts integral with a bracket 15 detach-ably secured by screws to the bed 22. Spring means is employed for yieldingly urging the work-table into its normal elevated work-presenting position determined by a stop-screw Ill which is threaded into the depending front wall 48 of the work-table 21,

the stop-screw ll at its inner end bearing against a stop-plate 49 (Figs. 1 and 2) secured by a screw 59' to an ear 5! cast on the bracket 35. Treadle or knee-shift controlled means is provided for pivotally lowering the work-table 2? about the eccentrically located ends 49 and 4! of' the work-table supporting shaft 42. This means preferably includes a rock-shaft 52 (Fig.

1) journaled in a bracket 53 attached to the base wand having secured to it a rock-lever 5d connected at its inner end by av wire-link 55 to the work-table 21. The rock-shaft 52 is extended to- .ward the front of the machine and is bent to extend across the front of and downwardly beneath the machine to form a knee-shift arm (not shown) which is adapted to carry av suit able knee-pad. Pressure applied to the kneepad causes the work-table 2's to tilt downwardly about its pivotal support,thus moving the tubular portion of the work-table away from the overlying presser-foot to release the work.

The spring means employed for yieldingly urging the work-table 21 into its elevated posi tion comprises a coil-spring 58 anchored at one end to a stud 5'! endwise adjustable inv the machine-frame, and at its other end connected to one end of a link 58 whose other end is connected to one limb of a bell-crank lever 59 pivoted at 60 on the ear 5!. The other limb of the bell-crank lever 59 is connected by a link 6! to the depending front wall 48 of the work- It will be understood that lowering inachine-standard 2 l.

4 2) to move toward the left and this movement of the link 6!, through the bell-crank 59, will cause the link 58 also to move toward the left, thereby extending the coil-spring 56. When the tre-adle or knee-shift is relieved of its pressure, the coil-spring 58 functions to return the worktable'2'! to its elevated position.

As is customary, work-table height adjusting means is provided for adjusting the normal elevated position of the work-table 21, thereby to regulate the depth of penetration of the curved needle in the formation of the blind-stitch. The means illustrated in the drawings for accomplishing the adjusting of the table height is identical with that disclosed in my copending application hereinbefore referred to and, as shown in Figs. 1 and 2, includes a manually controlled member, the actuation of which turns the workt'able supporting shaft 42 which, owing to the eccentrically disposed ends 49 and 4! thereof, results in bodily elevating or lowering the work table 2'5 relative to the stitching mechanism. In Fig. 2 it will be seen that the work-table height adjusting means comprises a rock-lever 62 clamped on the work-table supporting shaft 42 and having connected thereto one end ofa rearwardly extending link 53 which is connected at its other end to the lower end of a vertically disposed adjusting lever B l fulcrumed intermediate its ends on a pivot-stud 65 fixed in a lu 66 preferably cast integral with one wall of the At its upper end, the adjusting lever is formed as a yoke 6'! of which the parallel limbs are slotted, as at 68, to receive the side pins 69 of a block 10 which is threaded upon an adjusting screw H. The adjusting screw H is supported to turn but is confined against endwise movement in a detachable coverplate 12 provided for closing the open front face of the machine-standard 2|, and the adjusting screw has fixed thereto the manually controlled member which is in the form of a thumb disk 13. Indicia scribed in the peripheral face of the thumb-disk l3 facilitate the accurate adjustment of the normal elevated position of the work-table.

The work-table 2'! provides supporting means for the usual ridge-former 14 (Figs. 3, 4 and 9) which function in cooperation withthe presserfoot 24 in forming a bight in the material facilitating the penetration of the material by the curved needle 32 so as to form blind stitches.

In the machine illustrated, the ridge-former 14 is oscillated in the line of feed with the forward stroke of the ridge-former coinciding with the forward or advancing stroke of the feed, and also the ridge-former is bodily raised and lowered so that shallow or skip stitches can be formed between successive deep or anchor stitches. The present invention is directed particularly to the mechanisms for actuating the ridge-former, whereby it is oscillated and simultaneously therewith bodily raised and lowered to efiect presentation of the work to form skip stitches. Referring to, Figs. 2, 3 and 4, it will beseen that the ridge-former M is preferably clamped upon the left hand end-portion of a tubular ridgeformer carrying shaft 15 provided at its opposite ends with bearing bushings 16 by which the tubular shaft 15 is freely journaled on the enlarged ends ll of an eccentrically disposed body of a telescopically arranged skip-stitch shaft 18 journaled at one end in a bearing-lug "l9 and at its other end in a bearing-bracket det'ach'ably secured by a screw 8| and a pin 82 to the worktable 27-. At its right hand end, the tubular screws 88 threaded into the bushings.

level of the work-table 21. former" is in the extreme forward end of its shaft 15 has clamped on it a depending rocking bushings 81 fixed in the oppositewalls of the machine-standard 2|. The pivot-spindle 86 is confined in the bearing bushings 81 by two The rearwardly extending horizontal arm 89 of the bellcrank lever is connected to the lower end of a .pitman 90 whose upper end embraces an eccentric 9] fast on the main-shaft 30. Rotation of the main-shaft 30 will effect a complete osthe forward strokeof the ridge-former coincides with the work-advancing stroke of the feeding mechanism. sothat the friction resulting from the forming of the bight in the work will not seriously hinder or interfere with the feed of the work. The. height of the ridge-forming element 14 is normally set in accordance with the thickness of the material being sewn by manually adjusting the thumb-disk. 13 which regulates the When the ridgeoscillating stroke, the work is properly positioned .for penetration by the needle 32y (Figs.

l former 14. For example, Fig. 10 of the drawings discloses the ridge-former '14 in its upper or elevated position, wherein the plies of material are raised relative to the needle 32 to a point where the needle penetrate all the plies, while in Fig.

ll, the ridge-former is illustrated in its lower position, wherein the needle penetrates all but the bottom ply of the material. The means for periodicallyturning or oscillating the skip-stitch shaft 18 is best shown in Figs. 2, 3 and '7, and

"comprises a rock-lever 92 clamped on the right hand or distal end of the skip-stitch shaft 18 and having its lower end connected by a rear- .wardly extending pitman 93 embracing the outer race of aneedle-bearing 94 (Fig. '7) mounted on an eccentric 95 which is preferably formed integral with a belt sprocket 9E freely journaled on the skip-stitch pivot-spindle B6. A disk 91 is secured upon the end-face of the eccentric 95 and is sufficiently large in diameter to provide a flange for maintaining the needle-bearing 94 in proper position on the eccentric 95. The beltsprocket 95 is driven by a clip belt 98 which is driven from a smaller belt-sprocket 99 mounted on the main-shaft 30; the ratio of the beltsprockets 96 and 99 being such that the eccentric 95 rotates at half the speed of the main-shaft 30.

*When so operating, alternate skip and anchor stitches are produced. It will be understood that the ratios of the belt-sprockets 96 and 99 may also be of the order of 3-to-l or 4-to-1, in which case between each anchor stitch there will be formed three skip stitches or four skip stitches.

.As will be observed in Figs. 1 and 4, the inner skip-stitch shaft 19 has its opposite ends. journaled in the spaced bearing lugs I9 and with its right hand or distal end projecting beyond the bearing lug 19. The right hand end of the outer tubular shaft 15 terminates adjacentthe bearing lug 19 in a manner such that the rocklever 84 can be clamped on the outer tubular shaft adjacent one side face of the bearing lug 19, while on the distal. end of the inner shaft 18 the rock-lever 92 can be secured next to the opposite side face of the bearing lug 19. This arrangementcontributes to a rigid construction and permits the actuating connections 84 and, 93

for the outer and inner shafts l5 and 18 to be housed within the base 20 of the main-frame and to. transmit motion with a minimum of bending moment to the shafts 15 and 18 relative to their supporting bearings.

. Having thus set forth the nature of tion, what I claim here;n is:

1. In a blind-stitch sewing machine, the combination witha main frame including an overhanging arm, of a stationary presser-plate attached to the free end of said arm and provided with an opening, stitch-forming mechanism mounted on said arm and. including a needle mounted for movement across said opening,.,a work-table mounted on said main frame and having a portion underlying the free end of. said overhanging arm, a ridge-forming element located below saidpresser-plate forprojecting a ridge of fabric upwardly through said, opening into needle penetrating position, an oscillatory outer tubular shaft on which said ridge-forming element is mounted, an oscillatory inner shaft journaled in said Work-table and having at least one eccentrically disposed portion on which ,said tubular shaft is journaled, and actuating connections for oscillating said tubular and inner shafts at different frequencies thereby to raise and lower the field of action of said ridge-formthe invening element at intervals relative to said needle to form anchor stitches and skip stitches.

2. In a blind-stitch sewing machine, the combination with a main frame including an overhanging arm, of a main shaft journaled in said arm and extending longitudinally thereof, a stationary presser-plate attached to the free end of said arm and provided with an opening, stitchforming mechanism mounted on said arm and including a needle mounted for movement across said opening, a work-table mounted on said main-frame and having a portion underlying the free end of said overhanging arm, a ridge-forming element located below said presser-plate for projecting a ridge of fabric upwardly through said opening into needle penetrating position, an outer tubular shaft on which said ridge-forming element is mounted, an oscillatory inner shaft journaled in said work-table and having at least one eccentrically disposed portion on which said outer tubular shaft is carried,and actuating connections driven from said main-shaft for oscillating said inner shaft at a frequency diiferent from that of the needle.

3. In a blind-stitch sewing machine, the combination with a main frame including an overhanging arm, of a main shaft journaled in said arm and extending longitudinally thereof, a stationary presser-plate attached to the free end of said arm and provided with an opening, stitchforming mechanism mounted on said arm and including a needle mounted for movement across said opening. a work-table mounted on said main-frame and having a portion underlying the amt-ram 7 me end of said overhangin'g arm,:spaced-shaft eupportingibearing lugs provided on said work- 'table, a ridge-forming element .located below 'said presser-plateforprojecting a ridge of fabric upwardly through said opening into needle penc tr'ating position, 'aniouter tubular shaft located betu'reen s ai'd spaced bearing lugs. and having mounted thereon said ridge-forming element, an oscillatory inner shaft journaled insaid spaced b'earing lugs and having at least one eccentrically disposed portion on which said. outentubular shaft is carried, and actuating connections -driven from said main-shaft for oscillating said -}ihnerslhaft "at a frequency less than that of said jecting a ridge'o'f fabric upwardly through said opening into needlepenetrating position, an os- "cillatory outer tubular shaft located between said spaced bearing lugs and having mounted thereon said ridge-forming element, an oscillatory inner shaft'journaled in said spaced bearing lugs and h'aving a distal end portion extending beyond "the first of said bearing lugs, said inner shaft having at least one eccentricaliy disposed portion on which said outer tubular shaft is carried, a rock-lever secured on said tubular shaft-adjacent one side of said flrstbearing lug, a second rock-lever secured on the distal end of said inner shaft adjacent the other side of said first bearing lug, and actuating connections driven by said main-shaft and operatively assoelated with said rock "levers for imparting 'osci'llation of different frequencies to said outer and inner shafts;

*5. Ina blind-stitch sewing machine, the combination with a mainframe having a 'base', a

"standard and an overhanging arm, of a main shaft journal'ed insaid arm and extending lon- 'gitudinally thereof, a stationary presser-plate attached to'the free'end of said arm and 'pro- I 'vided with an: opening, stitch-forming *mechanism mounted on said arm and" including a needle mounted for movement across-said opening,"a work-table mounted on said base and having a portion underlying the free-end of said overhanging arm, a ridge-forming element 10- c'ated below said presser-plate for projecting a iidge'of fabric upwardly through said opening into needle penetrating position, an oscillatory outer-tubular shaft on which said ridge-forming element is mounted, an oscilla'tory inner shaft .journaled insaid work-table and havin an eccentrically disposed portion on which said outer tubular shaft is carried, a pivot-spindle mounted in said standard below the level of said main shaft, operating connections for saidouter tubularshaft including'an element journaled on H said pivot-spindle and driven from said inain- -shaft,-and operating connections for .said inner shaft including a rotary actuator journaled on tions for said said pivot-spindle and driven from said mainshaft.

' 6. Ina blind-stitch sewing machine, the com-- bination with a main frame having a base, a standard and an overhanging arm, of a main shaft journaled in said arm and extending longitu'dinally thereof, a stationary presser-plate attached to the free end of said arm and provided with an opening, stitch-forming mechanism mounted on 'said arm and including a nee'dle'mountecl for movement across said opening, a work-tablemounted on said base and havin a portion underlying thefree end ofisaid overhanging arm, a ridge-forming element located below said presser-plate for projecting a ridge of fabric upwardly through said opening into needle penetrating position, an. oscillatory outer tubular shaft on which said ridge-forming element is mounted, an oscillatory inner shaft journaled in said work-table and having an eccentrically disposed portion on which said outer tubular shaft is carried, a pivot-spindle mounted in said standard below the level of said mainshaft, actuating connections operated by said 'main-shaft for imparting oscillations to said outer tubular shaft, actuating connections for said inner shaft including a rotary actuator journaled on said pivot-spindle,zand a belt connecting said rotary actuator to said main-shaft.

7. In a blind-stitch sewing machine, the combination with a main frame having a base, a standard and an overhanging arm, of a mainshaft iournaledin said arm and extending longitudinally thereof, a stationary presser-plate attached to the free end ofsaid arm and provided with an opening, stitch-forming mechanism mounted on said arm and including a needle mounted for movement across said opening, a work-tablemounted on said base and having a portion underlying the free end of said overhanging arm, a ridge-forming element located below said presser-plate for projecting a ridge 'of fabric upwardly through said opening into needle penetrating position, an oscillatory outer tubular shaft on which said ridge-forming element is mounted, an oscillatory-inner shaft journaled in said work-table and having an eccentrically disposed portion on which said outer tubular shaft is carried, a pivot-spindle mounted in said standard below the level of said main-shaft, operating connections for said outer tubular shaft including an eccentric mounted on said main-shaft, a bell-crank lever journaled on said pivot-'spind1e, a pitinan connecting said 'be1l crank lever tosaid-eccentric, a link connected to said'bell-crank lever, and a rock-arm'connected at one end to said link and at itsother end to said outertu'bular shaft, and operating connecinner shaft including a second eccentric journaled on said pivot-spindle, means connected to said main-shaft for driving said second eccentric at a speed less than that of said main shait, a pitman connected to said second eccentric, and a rock-leverconnected at onelend to said pitman and at its other endto said inner shaft.

(8. In a blind-stitch sewing machine, the combinationwith a main frame having a base, a

standard andan overhanging arm, of a -mainshaft ,journaled in saidarm and extending 10n- -gitudinally thereof, a stationary presser-plate attached to the free end of said arm and provided mounted for movement across said opening, a work-table mounted on said base and having a portion underlying the free end of said overhanging arm, a ridge-forming element located below said presser-plate for projecting a ridge of fabric upwardly through said opening into needle penetrating position, an oscillatory outer tubular shaft on which said ridge-forming element is mounted, an oscillatory inner shaft journaled in said work-table and having an eccentrically disposed portion on which said outer tubular shaft is carried, a pivot-spindle mounted in said standard below the level of said main-shaft, operating connections driven by said main-shaft for imparting oscillatory movements to said outer tubular shaft, and operating connections for imparting oscillatory movements to said inner shaft including an eccentric mounted on said pivotspindle, actuating connections between said eccentric and said inner shaft, a first belt-sprocket associated with said eccentric, a second beltsprocket of smaller diameter than said first beltsprocket mounted on said main-shaft, and a belt connecting said two belt-sprockets together.

9. In a blind-stitch sewing machine, the combination with a main frame including a hollow base U-shaped in cross-section and having an open top, a hollow standard having its side walls formed as continuations 0f the side walls of said base and having its front side open to form with the open top of said base a continuous opening extending from the front of the base to the top of the standard, and an overhanging arm extending laterally from the standard, of a stationary presser-plate attached to the free end of said arm and provided with an opening, stitch-forming mechanism supported on said arm and including a needle mounted for endwise movement across said opening, a main-shaft J'ournaled in the overhanging arm and having one end projecting into the upper end of said standard, a work-table mounted on said base and having one end-portion enlarged to overhang the front endportion of said base, a ridge-forming element located below said presser-plate for projecting a ridge of fabric upwardly through said opening into needle-penetrating position, an oscillatory outer tubular ridge-forming element carrying shaft located in said work-table, an inner skipstitch shaft journaled in said work-table and having an eccentrically disposed portion on which said outer tubular ridge-forming element carrying shaft is journaled, said outer and inner shafts having one end located in that portion of the work-table which overhangs said hollow base, actuating connections driven from such mainshaft for each of said inner and outer shafts, said actuating connections extending from said inner and outer shafts downwardly into said hollow base then backwardly within said hollow base to said hollow standard and then upwardly through said hollow standard to said main-shaft, and a cover plate closing said open-topped base and open-sided standard to cover and conceal said actuating connections.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,828,789 Strobel Oct. 27, 1931 r 2,194,149 Mueller Mar. 19, 1940 

